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Fish predation is often cited as a key process in structuring sea urchin populations on coral reefs, with population outbreaks often being related to the removal of key predators through overfishing. However, moderate–high densities of the sea urchin Echinometra mathaei have been reported on a reef with relatively intact predator assemblages; Ningaloo Reef, Western Australia. This study examined the relationship between the densities of E. mathaei and its potential predators, to gain some insight into the potential role of predation in structuring E. mathaei populations on Ningaloo Reef. To identify potential urchin predators we recorded predation events on tethered E. mathaei using stationary video cameras. Seven fish species preyed on the tethered urchins with two labrid species, Coris aygula and Choerodon rubescens, accounting for 65% of all observed predation events. There was, however, no evidence for the role of predation in determining E. mathaei populations either within or among habitats. Despite the densities of E. mathaei varying from 0.1 to 219.7 ind 100 m− 2 among habitats, the density and biomass of potential urchin predators displayed limited variation among habitats. Furthermore, the density of E. mathaei was positively related to that of their predators on the reef slope and the back reef. While the overall density of potential predators (53.3 ind ha− 1) was comparable to other protected reefs, the suite of predators differed from that of other regions. In particular, large triggerfish species (f. Balistidae), the dominant predators of E. mathaei on other Indo-Pacific reefs, were rare or absent. While the lack of these species may have contributed to the moderate–high densities of E. mathaei on Ningaloo Reef, other factors such as larval supply, food availability and habitat characteristics may be important. Irrespective of the mechanisms, moderate–high densities of E. mathaei should not be universally viewed as an indicator of reef degradation.

The standardized karyotype and idiogram of the titan triggerfish, Balistoides viridescens (Bloch & Schneider 1801) from Phuket Province, Thailand, were obtained from the present study. Kidney cell samples were taken from five male and five female fish. The mitotic chromosome preparations were conducted directly from the kidney cells. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results indicated that the diploid chromosome number of B. viridescens was 2n=44, and the fundamental number (NF) was 60 in both sexes. The chromosome types consist of 2 large metacentric, 4 large acrocentric, 2 large telocentric, 8 medium acrocentric, 10 medium telocentric, 2 small acrocentric, and 16 small telocentric chromosomes. No strange-sized chromosomes related to sex was observed. The region adjacent to the subtelomeric of short arm of chromosome pair 3 showed clearly observable secondary constriction/NORs. The karyotype formula for B. viridescens is as follows: 2n (diploid) 44=L2 +La 4+L2+M8+M10+S 2+S16

Sex change is known from various fish species. In many polygynous species, the largest female usually changes sex to male when the dominant male disappeared, as predicted by the classical size-advantage model. However, in some fishes, the disappearance of male often induces sex change by a smaller female, instead of the largest one. The halfmoon triggerfish Sufflamen chrysopterum is one of such species. We conducted both field investigation and theoretical analysis to test the hypothesis that variation in female fecundity causes the sex change by less-fertile females, even if they are not the largest. We estimated the effect of body length and residual body width (an indicator of nutrition status) on clutch size based on field data. Sex-specific growth rates were also estimated from our investigation and a previous study. We incorporated these estimated value into an evolutionarily stable strategy model for status-dependent size at sex change. As a result, we predict that rich females change sex at a larger size than poor ones, since a rich fish can achieve high reproductive success as a female. In some situations, richer females no longer change sex (i.e. lifelong females), and poorer fish changes sex just after maturation (i.e. primary males). We also analyzed the effect of size-specific growth and mortality.

In diverse tropical webs, trophic cascades are presumed to be rare, as species interactions may dampen top-down control and reduce their prevalence. To test this hypothesis, we used an open experimental design in the Galapagos rocky subtidal that enabled a diverse guild of fish species, in the presence of each other and top predators (sea lions and sharks), to attack two species of sea urchins grazing on benthic algae. Time-lapse photography of experiments on natural and experimental substrates revealed strong species identity effects: only two predator species–blunthead triggerfish (Pseudobalistes naufragium) and finescale triggerfish (Balistes polylepis)–drove a diurnal trophic cascade extending to algae, and they preferred large pencil urchins (Eucidaris galapagensis) over green urchins (Lytechinus semituberculatus). Triggerfish predation effects were strong, causing a 24-fold reduction of pencil urchin densities during the initial 21 hours of a trophic cascade experiment. A trophic cascade was demonstrated for pencil urchins, but not for green urchins, by significantly higher percent cover of urchin-grazed algae in cages that excluded predatory fish than in predator access (fence) treatments. Pencil urchins were more abundant at night when triggerfish were absent, suggesting that this species persists by exploiting a nocturnal predation refuge. Time-series of pencil urchin survivorship further demonstrated per capita interference effects of hogfish and top predators. These interference effects respectively weakened and extended the trophic cascade to a fourth trophic level through behavioral modifications of the triggerfish-urchin interaction. We conclude that interference behaviors capable of modifying interaction strength warrant greater attention as mechanisms for altering top-down control, particularly in speciose food webs.

Visual illusions occur when information from images are perceived differently from the actual physical properties of the stimulus in terms of brightness, size, colour and/or motion. Illusions are therefore important tools for sensory perception research and from an ecological perspective, relevant for visually guided animals viewing signals in heterogeneous environments. Here, we tested whether fish perceived a lightness cube illusion in which identical coloured targets appear (for humans) to return different spectral outputs depending on the apparent amount of illumination they are perceived to be under. Triggerfish (Rhinecanthus aculeatus) were trained to peck at coloured targets to receive food rewards, and were shown to experience similar shifts in colour perception when targets were placed in illusory shadows. Fish therefore appear to experience similar simultaneous contrast mechanisms to humans, even when targets are embedded in complex, scene-type illusions. Studies such as these help unlock the fundamental principles of visual system mechanisms.

Coral reef fishes are among the most colourful animals in the world. Given the diversity of lifestyles and habitats on the reef, it is probable that in many instances coloration is a compromise between crypsis and communication. However, human observation of this coloration is biased by our primate visual system. Most animals have visual systems that are ‘tuned’ differently to humans; optimized for different parts of the visible spectrum. To understand reef fish colours, we need to reconstruct the appearance of colourful patterns and backgrounds as they are seen through the eyes of fish. Here, the coral reef associated triggerfish, Rhinecanthus aculeatus , was tested behaviourally to determine the limits of its colour vision. This is the first demonstration of behavioural colour discrimination thresholds in a coral reef species and is a critical step in our understanding of communication and speciation in this vibrant colourful habitat. Fish were trained to discriminate between a reward colour stimulus and series of non-reward colour stimuli and the discrimination thresholds were found to correspond well with predictions based on the receptor noise limited visual model and anatomy of the eye. Colour discrimination abilities of both reef fish and a variety of animals can therefore now be predicted using the parameters described here.

The prevalence of a haremic mating system type with parental care is one of the main characteristics of the modern triggerfish family (Balistidae). In addition, intraspecific modifications of the mating system in relation to environmental conditions have been recognized. Thirteen months of observation of mating units in a natural population of Rhinecanthus aculeatus from Okinawa Island, Japan, revealed that the mating system in this species involved a mixture of polygyny, monogamy, and potential promiscuity in solitary females. Females defended individual, multi-purpose territories, while males engaged in female defence (“female defence polygyny”) using displays and overt aggressions that advertised that territories were occupied. Male size was strongly linked to access to multiple females (i.e. polygyny). Plasticity in the mating system was related to male–male competition and the ability of females to reject males. An increase in the proportion of monogamous pair territories over the course of the reproductive season was positively correlated with the adult sex ratio (increased male density relative to females), and facultative monogamy was enhanced under a less female-biased sex ratio. A comparison between female and male mating success (number of matings) and the adjustment of the mating status over time revealed that polygyny was advantageous and the optimal mating system for males. Females achieved higher number of matings when pairing with larger males, but mating success was not negatively affected by the actual mating status, and females did not attempt to escape polygyny. Polygyny is therefore considered as the primary mating system in R. aculeatus.

To understand age and growth of the Picasso triggerfish, Rhinecanthus aculeatus, monthly sampling was conducted from February 2010 to October 2011 on the subtropical Okinawa Island, Japan, using trammel net and speargun. Fish were measured by weight (W) and standard length (SL) and age was determined by examining thin-sections of the first dorsal spine and the second abdominal vertebra. A total of 352 fish were caught ranging from 20.9 mm to 209.5 mm (SL). Marginal increment analysis indicated that translucent rings were deposited annually during the colder season from October to January. The relationship of observed SL and age was described by the original form of the von Bertalanffy growth equation. Male and female growth models were significantly different. Overall growth was rapid during the first 2.5 years for both sexes, thereafter growth curves diverged. Males consequently reached larger sizes and greater ages. Maximum age for males and females was 13.5 and 9.5 years, respectively. Regression models of somatic growth (SL) as a function of vertebral and spine radii were significantly correlated (r = 0.98 and r = 0.96, respectively). According to the weight–length relationship, growth in R. aculeatus was negative allometric. Small recruits (SL

We documented spawning behaviors in gray triggerfish, Balistes capriscus (Gmelin, 1789), in June and July 2004-2007 on artificial reefs in the northern Gulf of Mexico, including territoriality, nest building, harem spawning, and parental care. Males were significantly larger than females and could be distinguished from females by size and dark charcoal coloration during the spawning season. Pre-fertilization dominant males were observed building and maintaining one to 13 demersal nests at particular reef sites, aggressively defending the immediate area surrounding the nests against other male gray triggerfish and other fishes, while attracting one to five females to spawn. Pre-fertilization females were observed frequently visiting and inspecting the newly constructed nest. Post-fertilization females stayed continuously on the nest guarding the eggs, and displayed a contrasting white and black color pattern, while fanning and blowing the eggs. Post-fertilization males continued to defend a territory immediately around the nest, visiting the female on the nest, and chasing other fish away. Actual spawning behavior was observed where a male and female tightly circled each other within the nest, with fertilized eggs produced immediately after this circling. Active nests with a guarding female and male were observed 28 times on 18 different reef sites. Mean number of eggs per spawning event was 772,415 from 13 active nests each with a guarding female. Observations of aggressive male behavior and sex ratios of single dominant male and up to five spawning-condition females indicate that gray triggerfish display harem spawning behavior.

Gray triggerfish Balistes capriscus is a reef fish exploited by recreational and commercial fisheries in the southeastern United States. Recent stock assessments indicated that the species is overfished, and a rebuilding plan is in progress. The U.S. fishery is currently managed as a single stock owing to the absence of reliable information on stock structure. We sequenced a 617-base-pair fragment of the ND4 mitochondrial gene in a total of 150 specimens from five localities (South Texas, Louisiana, West Florida, southeastern Florida, and South Carolina) encompassing the exploited range of the species in the USA. Analysis of molecular variance, spatial analysis of molecular variance, and spatial autocorrelation analysis did not reveal significant spatial heterogeneity in haplotype distributions within the studied range. Significant departure from neutrality was inferred from neutrality tests and may reflect the signature of a rapid population expansion following the recent glacial epochs, an infe...

Innovations in locomotor morphology have been invoked as important drivers of vertebrate diversification, although the influence of novel locomotion strategies on marine fish diversification remains largely unexplored. Using triggerfish as a case study, we determine whether the evolution of the distinctive synchronization of enlarged dorsal and anal fins that triggerfish use to swim may have catalyzed the ecological diversification of the group. By adopting a comparative phylogenetic approach to quantify median fin and body shape integration and to assess the tempo of functional and morphological evolution in locomotor traits, we find that: (1) functional and morphological components of the locomotive system exhibit a strong signal of correlated evolution; (2) triggerfish partitioned locomotor morphological and functional spaces early in their history; and (3) there is no strong evidence that a pulse of lineage diversification accompanied the major episode of phenotypic diversification. Together these findings suggest that the acquisition of a distinctive mode of locomotion drove an early radiation of shape and function in triggerfish, but not an early radiation of species.

Recruitment of age-0 gray triggerfish Balistes capriscus to benthic artificial reefs was documented by diver surveys from 2003 to 2007. Divers counted and estimated the sizes of all gray triggerfish that recruited to three types of artificial reefs (all in 20-m depths) ranging from 1.2 to 4.0 m2 in area. Reefs were located in the Gulf of Mexico 28 km south of Dauphin Island, Alabama. Forty artificial reefs built in June 2003 were surveyed in October–December 2003 and May 2004; 20 artificial reefs built in October 2005 were surveyed in October and December 2005 and May, August, and December 2006; 40 artificial reefs built in July 2006 were surveyed in June 2007; and 30 artificial reefs built in August 2007 were surveyed in September, October, and December 2007. Recruitment patterns were similar in the fall and winter of 2003 and 2007. In 2005 significantly lower numbers of recruits were detected than in other years, which may have been caused by a major hurricane. Peak recruitment of age-0 gray tr...

1. This study presents a comparison of the benthic cover and fish communities in three widely different management systems: (1) a heavily utilized subsistence fishery (yields >5 Mg km−2 yr−1); (2) moderately sized and well enforced fisheries closures (∼9% of the nearshore area) surrounded by heavy fishing; and (3) a more lightly used management system (yields

Biodegradable films can act as excellent oxygen, water, and lipid barrier. Gelatin is utilized extensively as a gelling agent, emulsifier, stabilizer, adhesives, viscosity agent, binder agent and film-forming agent. Fish gelatin as a film-forming agent has unique characteristics but varies depending on fish species. The study aims to characterize biodegradable film made using skin and bone fish gelatin with the addition of plasticizer. Gelatin of ocean fish, spotted oceanic triggerfish (Canthidermis maculata), and freshwater fish, tilapia (Oreochromis niloticus) were used. As a plasticizer, glycerol or sorbitol with concentrations of 0.25 and 0.5 % was added. Gelatin of spotted oceanic triggerfish resulted in film with higher tensile strength, whereas tilapia gelatin with glycerol produced biodegradable film with higher elongation and water vapor permeability. The best characteristics of biodegradable film made from gelatin of spotted oceanic triggerfish with 0.25% sorbitol.

Paternal care is predominant among telcost fishes with external fertilization. This study describes maternal care in a haremic coral-reef fish and discusses the possible factors leading to its evolution. Both sexes of the triggerfish Rhinecanthus aculeatus (Balistidae) maintained territories; some individuals for more than 8 years. Each male's territory overlapped 2-3 female territories. Pair-spawning occurred around sunrise. Only females cared for the demersal eggs until hatching, which occurred just after sunset on the day of the spawning. No predation was observed on eggs under the maternal care, but experimental removal of parental females decreased the hatching rate to nearly zero. Egg-guarding females foraged as frequently as males, but less than half of non-spawning days. Spawning occurred only in the periods of about 1 wk around the new or full moon, and individual females spawned up to three times in each period. Thus, the maternal care did not significantly affect the duration of the females' spawning intervals, while males would suffer mate loss if they performed parental care. In this situation, maternal care should be the evolutionarily stable strategy. Evolutionary transition from no care to maternal care and then to biparental care is suggested in the Balistidae.

Groups of the triggerfish Pseudobalistes fuscus and Odonus niger were studied from the underwater laboratory Neritica in Eilat, Gulf of Akaba, in the Red Sea. Mating and the roles of the sexes during broodcare seem to depend strongly on territory size, probably determined by shelter site and food availability, and territorial control- and defendability. The discussion considers why evolution has favoured maternal broodcare in the one case and biparental in the other.

The snapper-grouper fishery off the coast of the southeastern United States contains many exploited species that are governed under a multitude of species-specific regulations. Despite ample information on landed commercial catches, there is a critical need to characterize the entire commercial catch to identify catch composition, discard proportion and immediate release mortality proportions. This study recorded the lengths of all fish caught on a commercial snapper-grouper vessel and their subsequent disposition. Over 40 fishing days, the captain captured 55 species, but the majority of the catch (97%) was comprised of just 8 species (vermilion snapper, gray triggerfish, red porgy, black sea bass, tomtate, scamp, greater amberjack, and Almaco jack). Discard proportions were low overall, but varied by species, while immediate release mortality proportions were generally high (>40%). Species with high discard proportions were red porgy (56%), scamp (44%), bank sea bass (46%), and red snapper (42%). Three of these species also had high immediate release mortality proportions: red porgy – 82%, scamp – 98%, and red snapper – 93%. Species with both high discard proportions and high immediate release mortality proportions might indicate that current management regulations are not adequately protecting these stocks, as a large number of discarded fish do not survive.

Unlike other balistids, grey triggerfish Balistes capriscus occur in social groups in subtropical reef assemblages and have been noted to cooperate in capturing large crustacean prey. The objective of this study were to determine the structure of dominance hierarchies of these social groups and the factors that influence hierarchies of wild-caught grey triggerfish in a naturalistic setting. From observations of four groups of triggerfish (n = 19 fish) in both dyad and group (4 - 5 fish) settings, we provide a description of triggerfish behaviors and coloration patterns and an explanation of the social context in which suites of behaviors are used by dominant, middle-ranking, and subordinate fish. Sixteen behaviors and nine coloration patterns were noted for grey triggerfish. Grey triggerfish groups form linear hierarchies in both dyads and groups as measured by Landau's Index of Linearity (h = 1.0 for Groups 1, 3, and 4 and h = 0.95 for Group 2 in dyads; h = 1.0 for all groups in group settings). Dyadic hierarchies, however, were not necessarily good predictors of the hierarchies found in larger group settings, as they only predicted two of the four group hierarchies. Sex played no role in influencing status or behavior. Size had the greatest influence on dominance status, with larger fish being more dominant than smaller fish. An individual's dominance ranking influenced both body coloration and posture. These results suggest that color patterns and body postures may also be used by observers as an indicator of an individual's social status in groups.

Reef fishes were compared between artificial reefs with (n = 20) and without (n = 20) epibenthic communities in the northern Gulf of Mexico. Artificial reefs were built in June 2003; half were coated with copper-based paint to prevent epibenthic community development. Reefs were surveyed by SCUBA divers to estimate fish abundance in the autumn and winter 2003 and spring 2004. Total fish abundance and abundance of red snapper, Lutjanus campechanus (Poey), and gray triggerfish, Balistes capriscus Gmelin, were significantly (P ≤ 0.05) higher on reefs with epibenthic communities. In the spring 2004, the abundance of belted sandfish, Serranus subligarius (Cope), the size of red snapper and community measures of diversity and evenness were significantly (P ≤ 0.05) greater on unpainted reefs. These significant differences provide evidence that reef fishes were positively affected by the presence of epibenthic organisms that probably provided increased food resources.

Migrating queues of Caribbean spiny lobsters, Panulirus argus, suffer attacks during daylight by variable numbers of triggerfish they encounter on patch reefs. When threatened, lobsters assemble into outward facing, rosette‐like groups, remain coherent in their spacing, and defend themselves by parrying with their spinous antennae. In 90‐min field tethering trials involving predatory grey triggerfish (Balistes capriscus), solitary lobsters were subdued 44% of the time whereas grouped lobsters suffered only minor bites; triggerfish present numbered from 1 to 23. Victims of fish attack were significantly smaller than survivors in the field trials. Although attack/defense ratios did not differ between solitary and grouped lobsters, fish behaviours towards such different groups did differ with more bite attempts/bites being directed towards solitary lobsters. In a series of experiments in large seawater enclosures, we pitted 1, 3, 5, 10, or 20 free‐moving lobsters against 2 or 5 grey triggerfish, all...

Stock assessments indicate many reef fish species have declined in size and abundance in the Atlantic Ocean off the southeastern coast of the United States. However, commercial fishers often state that stock assessments do not match their observations. We compared fishery-independent catch per unit effort (CPUE) and species composition data between the 1970s and 2005-2006 for reef fishes in the vicinity of Onslow Bay, North Carolina. Additionally, total mortality (Z) was estimated by means of a length-based catch-curve analysis. Effort (drops) by rod and reel focused on three sites, two inshore (30 m deep) and one offshore (125 m). The CPUE was compared between periods within each site and larger area (inshore, offshore). The CPUEs of red porgy Pagrus pagrus, vermilion snapper Rhomboplites aurorubens, black sea bass Centropristis striata, and gray triggerfish Balistes capriscus were greater in the 1970s than in 2005-2006 at specific capture sites. Conversely, the CPUEs of red grouper Epinephelus ...

The spiny lobster, Panulirus argus, is predominantly nocturnal, remaining inside shelters during the day and foraging outside at night, presumably to minimize predation risk. Predation risk generally decreases with increasing lobster size. Therefore, this study examined the hypothesis that size would influence this basic circadian pattern. Video cameras continuously recorded the shelter occupancy of juvenile lobsters (n = 72) having a carapace length (CL) of 30–62 mm that were tethered to shelters in a shallow reef lagoon. The lobsters’ shelter occupancy was 100% during the day, but declined linearly from shortly before sunset to a minimum of 50% shortly after midnight and then increased linearly, reaching 100% by 1 h after sunrise. The percent time the lobsters spent in the shelters followed a similar trend, but there was wide variability at night (0–100%) for individual lobsters. Lobsters left their shelters 2–30 times night−1, with a majority of excursions lasting 80 mm CL), which have a dusk/early evening peak in activity and leave the shelter for extended periods of time during the night. Furthermore, a minimum shelter occupancy in the middle of the night appears especially well adapted to avoid exposure to daytime predators. Videotaped observations also included interactions between lobsters and two dominant lobster predators, the triggerfish, Balistes capriscus, and the octopus Octopus cf. vulgaris. Lobsters responded differently to these predators: remaining in the shelter when attacked by a triggerfish and fleeing the shelter when attacked by an octopus. Triggerfish were nearly twice as likely to attack a lobster that was outside of the shelter than inside. Once under attack, however, a lobster had nearly the same chance of surviving if it was inside or outside. Results suggest that the patterns of shelter use and emergence change as lobsters grow, probably reflecting the interplay between perception of predation risk and the need to forage.

Monthly visual surveys of reef fish populations in the Florida Keys were conducted from May to September of 1999 and April to December of 2000 using both strip transect and stationary point count sampling methods. Each month divers using SCUBA conducted three 10 m × 30 m transect surveys and three 5 m radius stationary point counts at 26 sites selected using a habitat based, stratified random design procedure. During both sampling procedures divers enumerated and assigned to 5 cm size increments all groupers (Serranidae), snappers (Lutjanidae), hogfish (Labridae), angelfish (Pomacanthidae), butterflyfish (Chaetodontidae), triggerfish (Balistidae), and a few other species of recreational or commercial importance. The rationale behind this sampling design was to assess the differential vulnerability of the various species and size classes to the lower behavioral disturbance/smaller area point count technique as compared to the higher disturbance/larger area transect method, and to assess which method would produce the highest density estimates and census the largest number of individuals per unit of sampling effort for size structure determinations. Although both types of samples required about the same amount of diver effort to complete, approximately 1.5 times more individuals were recorded during transect surveys. However, since transect surveys encompassed 4.3 times as much area as point counts, observed densities averaged about three times higher for point count samples. There was considerable variation among species with respect to this pattern, with total numbers of individuals for the 10 most abundant species ranging from about equal to 4.5 times higher during transect surveys, while densities ranged from nearly equal to about 6 times higher during point counts. Length frequencies within species were generally very similar between the two methods, though a higher proportion of larger individuals was recorded for a few species during transect surveys. Since previous studies have strongly indicated that visual census techniques produce underestimates of true reef fish densities, the higher and presumably more accurate density estimates provided by the point count method, along with other factors such as presumed increases in accuracy of counts and size estimates associated with increased observation time of individual fishes, led us to select this method for our future surveys.

Species-specific enemies may promote prey coexistence through negative distance- and density-dependent survival of juveniles near conspecific adults. We tested this mechanism by transplanting juvenile-sized fragments of the brooding coralsPocillopora damicornisandSeriatopora hystrix3, 12, 24 and 182 cm up- and down-current of conspecific adults and monitoring their survival and condition over time. We also characterized the spatial distribution ofP. damicornisandS. hystrixwithin replicate plots on three Fijian reef flats and measured the distribution of small colonies within 2 m of larger colonies of each species. Juvenile-sized transplants exhibited no differences in survivorship as a function of distance from adultP. damicornisorS. hystrix. Additionally, bothP. damicornisandS. hystrixwere aggregated rather than overdispersed on natural reefs. However, a pattern of juveniles being aggregated near adults while larger (and probably older) colonies were not suggests that greater mortality near large adults could occur over longer periods of time or that size-dependent mortality was occurring. While we found minimal evidence of greater mortality of small colonies near adult conspecifics in our transplant experiments, we did document hot-spots of species-specific corallivory. We detected spatially localized and temporally persistent predation onP. damicornisby the territorial triggerfishBalistapus undulatus. This patchy predation did not occur forS. hystrix. This variable selective regime in an otherwise more uniform environment could be one mechanism maintaining diversity of corals on Indo-Pacific reefs.

International audience; Characterizing the vulnerability of both target and non-target (bycatch) species to a fishing gear is a key step towards an ecosystem-based fisheries management approach. This study addresses this issue for the tropical tuna purse seine fishery that uses fish aggregating devices (FADs). We used passive acoustic telemetry to characterize, on a 24 h scale, the associative patterns and the vertical distribution of skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), and bigeye tuna (Thunnus obesus) (target species), as well as silky shark (Carcharhinus falciformis), oceanic triggerfish (Canthidermis maculata), and rainbow runner (Elagatis bipinnulata) (major non-target species). Distinct diel associative patterns were observed; the tunas and the silky sharks were more closely associated with FADs during daytime, while the rainbow runner and the oceanic triggerfish were more closely associated during the night. Minor changes in bycatch to catch ratio of rainbow runner and oceanic triggerfish could possibly be achieved by fishing at FADs after sunrise. However, as silky sharks display a similar associative pattern as tunas, no specific change in fishing time could mitigate the vulnerability of this more sensitive species. For the vertical distribution, there was no particular time of the day when any species occurred beyond the depth of a typical purse seine net. While this study does not provide an immediate solution to reduce the bycatch to catch ratios of the FAD-based fishery in the western Indian Ocean, the method described here could be applied to other regions where similar fisheries exist so as to evaluate potential solutions to reducing fishing mortality of non-target species.

This chapter discusses the effect that glaucoma has on the intraocular pressure (IOP) within the eye and related tonometer techniques are used to measure the changes in IOP. The relationship and subsequent analysis between corneal deformations and IOP is presented together with a review of the Triggerfish (Sensimed) smart contact lens.

Fishing disturbance can have indirect negative effects on animal behavior and survival, but receives little attention compared to measures of direct fisheries extraction. We quantified changes in the density of Caribbean spiny lobster Panulirus argus when exposed to experimental human disturbance and injury typical of sport-diver harvest attempts in the field. A complementary study in a large seawater arena quantified lobster sheltering behavior and survival when exposed to the single and combined effects of human disturbance and triggerfish Balistes capriscus predators. Human disturbance and injury of lobsters in the field caused lobsters to emigrate from shelters that had been typically occupied over successive days. Similarly, both the presence of triggerfish predators and human disturbance promoted decreased lobster shelter fidelity to individual shelters in the arena. Overall shelter use and gregariousness increased in the presence of natural triggerfish predators but not as a function of human disturbance. Decreased shelter use and gregariousness by lobsters when exposed to human disturbance may have contributed to their decreased survival when exposed simultaneously to triggerfish. These results highlight how human disturbance and injury of lobsters can alter their behavior and reduce subsequent survival in the presence of their natural predators, and illustrate the need to incorporate the negative effects of sport-divers into models that estimate population demographic rates.

The remarkable swarming of black triggerfish Melichthys niger (Balistidae) on oceanic islands led us to undertake a comparative ecological study of high-density and low-density populations of this unusual circumtropical species. Abundance, distribution, and aggressive encounters were recorded in the field from the high-density Johnston Atoll (JA) population, the low-density Belize (BE) population, and a local high-density aggregation from Puerto Rico (PR). JA and PR populations of M. niger occurred at significantly higher densities and were more aggregated than in BE. Intraspecific aggression (chases/min/fish) was an order of magnitude higher in BE than in JA, while interspecific aggression was similar among sites. Size frequency, growth rate, diet composition, body condition (liver-somatic index LSI) were assessed from collected specimens. JA grew more slowly than BE as determined by back-calculations from dorsal spine rings, suggesting density-dependent growth limitation. Size frequency analysis reflected this difference with significantly more large fish in the BE sample. Maximum age of triggerfish in both populations was estimated at 11 years, and 35–40% of growth occurred in the first year. Diet composition was similar in all three locations and indicated broad omnivory. Percent organic composition of gut contents (food quality measure) and LSI (body condition assay) were both significantly higher in the PR population, but no difference was detected between JA and BE. An increase in consumption of algae on the degraded PR reef may explain this pattern.

The congeneric spiny lobsters Panulirus argus and P. guttatus co-occur throughout the Caribbean Sea, where they may share the coral reef habitat. Despite their phylogenetic closeness, both species have many different life-history traits that may partially explain their coexistence. However, even though both species may face the same predators, their defense mechanisms and antipredator strategies had not been compared. We compared the performance between species in 18 morphological and behavioral defense mechanisms commonly expressed by most spiny lobsters, including predator-avoidance mechanisms (activity schedule, sheltering behavior, delay to disturbance, and effect of conspecific damage-released scents on shelter choice) as well as antipredator mechanisms (body size, several parameters of the escape response and limb autospasy, clinging strength, antennal strength, and cooperative defense). As hypothesized, both species expressed all these defense mechanisms (except cooperative defense, shown only by P. argus), reflecting their phylogenetic closeness, but performed significantly differently in most, in accordance with their particular ontogenetic traits. Their comparative performance in individual defense mechanisms as well as the antipredator strategies displayed by groups of lobsters of each species in the presence of a common predator (the triggerfish Balistes vetula) showed that, in general, the defensive behavioral type of P. argus is more bold and that of P. guttatus more shy. Therefore, their distinct defensive behaviors contribute to their niche differentiation.

Eight polymorphic microsatellites in the gray triggerfish, Balistes capriscus, are presented. For 24 genotyped individuals, the number of observed alleles per locus ranged from 10 to 21 (mean = 15), and observed heterozygosity varied between 0.708 and 1.000. Genotypic frequencies did not deviate significantly from Hardy–Weinberg equilibrium proportions, and there was no evidence of null alleles or linkage disequilibrium among loci. These microsatellite loci are additional markers for fisheries managers to utilize in population-level B. capriscus assessments.

It has been, in general, known that the catching efficiency of a trammel net is better than that of a gill net because of the variability of catch species and size. In this stidy, A fishing gear test was carried out to analyze the catching efficiency of the gill net and the trammel net on the coast of Geomun-do of southern Korean waters and fish school aggregation was also investigated using a underwater video camera. CPUE of the gill net was 49.2% higher than the trammel net but fish species was 34.5% lower where there was no difference on the significance level of 5% by ANOVA test. Main catch species caught by the gill net were red seabream(Pagrus major) and triggerfish(Aluterus monoceros), skate ray(Raja Kenojei) and red seabream for the trammel net, and the average body length of red seabream was shorter than the trammel net. It was thought that the reason of higher catch in the gill net than the trammel net was a fish school which can be caught easily by gill net and the size of population was suitable for the gill net.

A new species of triggerfish, Abalistes filamentosus is described on the basis of 17 specimens collected at depths from 61 to 180 m in Japan, the Northwest Shelf of Australia, and the Timor Sea. It differs from the congener, A. stellatus (Anonymous, 1798), by having filamentous upper and lower caudal-fin rays, 3-4 longitudinal grooves on the cheek, and by lacking yellow/pale blue spots and yellow reticulations on the body. The new species is not sexually dimorphic. The authorship of Abalistes stellatus is clarified.

The yellow-spotted triggerfish (Pseudobalistes fuscus), a member of the genus Pseudobalistes, belongs to the family Balistidae. Here, we describe the complete mitochondrial genome sequence of P. fuscus. The genome, 16,480 bp in length, is comprised of 13 protein-coding genes, 22 tRNAs, 2 rRNAs and a major non-coding region. The gene content and order are in accord with the common vertebrate form. A phylogenic tree was constructed based on the complete mitogenomes of P. fuscus and six closely related species to estimate their phylogenic relationship. Our data present an important genetic resource for the biological studies of the family Balistidae.

Postmortem changes of Finescale triggerjish muscle during 20 days of storage at OC were evaluated by monitoring changes in chemical, biochemical and microbiological parameters. The K value increased linearly fi-om an initial value of 3.5% to 43.3% at day 20. pHfluctuatedfiom 6.38 to 6.55. TMA-Nand TYB-N remained below critical limits with final values of 1.18 mg TMA-NAOO g muscle and 29.7 mg TVB-N/lOO g muscle, respectively, suggesting a low microbial activity. Composition of muscle protein fractions was not aflected during the storage period; however, an initial high level of alkali-soluble protein was detected. The overall results indicated that triggerfish has excellent shelf-life on ice.

Reproductive ecology of the crosshatch triggerfish, Xanthichthys mento (Balistidae) was studied at Hachijojima, Izu Islands, Japan. Males established territories and repeatedly chased females passing nearby. There were 1–3 females in each male's territory before spawning and during egg care. This species spawned in pairs on the sandy bottom. Eggs were scattered and attached to sand particles. Females care for the eggs by blowing water on them and guarding them against intruders, while males helped in guarding. Thus, biparental egg care was observed for 2 days until hatching. Both the males and females disappeared from the territories after the egg care. The reproductive ecology of this species is compared with that of other balistids and the unique features of X. mento are described.

We compared the antipredator mechanisms of 3 morphological 'types' of lobsters: slip- per lobsters Scyllarides latus, spiny lobsters Palinurus elephas and clawed lobsters Homarus gam- marus. These lobsters differ in the extent and effectiveness of their weaponry and armor, which we assessed by: (1) field tethering experiments that compared relative survival of intact and manipulated (clinging ability, antennae, or claws removed) lobsters in the face of predation, and (2) measurements of the breaking strength and thickness of the carapace of each species. Intact clawed lobsters suffered higher mortality than either intact slipper or spiny lobsters after both 4 and 24 h. At 24 h, intact spiny lobsters also had higher mortality than intact and manipulated slipper lobsters. The intact spiny and clawed lobsters suffered less predation after 4 h than the manipulated lobsters (lacking weapons); however, this advantage diminished or vanished by 24 h. This indicates that weapons pro- vided some measure of protection in the short-term, which might be sufficient to allow the lobsters to escape from a predator using a strong abdominal tail flip. Triggerfish Balistes carolinensis were the primary predators on the lobsters. We also saw octopuses Octopus vulgaris feeding on lobsters, but these were never observed subduing a live lobster. 'Punch'-tests (i.e. puncture tests) on the carapaces of each of the 3 species showed that slipper lobsters had stronger armor than either spiny or clawed lobsters, while the spiny lobster armor was intermediate in strength. These results suggest that the defensive strong armor of slipper lobsters is a more effective antipredatory mechanism than the offensive morphological weapons of the spiny and clawed lobsters.

Twenty one microsatellite markers were isolated from two enriched genomic libraries of the gray triggerfish, Balistes capriscus. The number of alleles detected varied between 4 and 27, and expected heterozygosity estimates ranged from 0.502 to 0.967 (n = 35). Genotypic proportions conformed to Hardy–Weinberg expectations for all but two of the loci. The microsatellite markers developed in this work will be precious to conservation genetics studies of the gray triggerfish.

On 3 August and 4 October 1995, Hurricanes Erin and Opal, respectively, passed directly over Pensacola, Florida in the Northern Gulf of Mexico. After the hurricanes, fishers and divers could not relocate many artificial reefs in the area. Extensive visual censuses of artificial reef assemblages had been conducted in the impacted areas in 1991-1993. This database provided the opportunity to examine the effects of hurricanes on artificial reefs, and the interaction effects of hurricanes and fishing pressure on the associated fish assemblages. Post-hurricane positions of 38 reefs in a permitted reef site, 14 km offshore, were determined by sonar and identified visually by divers. Materials of higher density were least affected by wave surge; however, a large steel vessel was broken into several pieces. Lighter (low-density) materials were moved distances of at least 1000 m. Comparisons of pre- and post-hurricane fish assemblages revealed a significant increase in average length of gag (Mycteroperca microlepis) and red snapper (Lutjanus campechanus). Because some reefs were displaced, fishing pressure was greatly reduced for at least 1 year. The new coordinates for a number of the relocated reefs were released to the public, thereby subjecting the fish assemblages to increased fishing pressure. Pre- and post-fishing comparisons indicated significant differences in biomass, number of gray triggerfish (Balistes capriscus), average length of gag, and number and average length of red snapper. These results, coupled with published information, indicate that artificial reefs may serve as refugia from fishery harvest following severe storms. This refugia function has potential utility in the design of marine reserves as well as offering an alternative strategy in the development of fishery management plans. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.

Age, growth and longevity of gray triggerfish Balistes capriscus from the coast near Sao Paulo were estimated from first dorsal spine sections of 1,800 fish. The translucent zone was formed during winter (June, July and August) and the reproductive period (December, January, February). The von Bertalanffy growth equations were: FL = 514.9 [1 - e -0.2625 (t + 0.0391)] for males, and FL = 504.6 [1 - e-0.2748 (t -0.0304)] for females. The longevity estimated was 11 years old for males and females. The instantaneous mortality rates estimated were 0.26 for males and 0.27 for females. The weight-length relationships for both sexes of gray triggerfish together were Wt = 0.000004 FL3.299.

The potential relationship between ecological versatility and local distribution and abundance for 5 species of triggerfish was examined at Kimbe Bay, Papua New Guinea. The abundances of juvenile and adult Balistapus undulatus, Melichthys vidua, Rhinecanthus verrucosus, Sufflamen bursa and S. chrysopterus were quantified in a range of habitats along a typical coral reef profile. Four of the 5 species displayed distinct and relatively narrow distributions across the reef profile, with the fifth species, B. undulatus, being broadly distributed across all zones and depths, and the most abundant species. For each species, the spatial distribution of juveniles closely matched that of adults and juvenile densities were greater in species with more abundant adults. A detailed description of depth distributions of individuals indicated that shallow species had narrower depth ranges. In terms of microhabitat use, B. undulatus was the most generalised species, occupying all the microhabitats that were identified. The other 4 species were specialised to varying degrees on different microhabitats. Results from this study provide the first detailed description of patterns of distribution and abundance, habitat use and ecological versatility in triggerfish. Distribution and abundance could partially be explained by differences in the degree to which each species is specialised, both in terms of depth and microhabitat selectivity. Hence, versatility in depth and microhabitat use may play an important role in determining the local distribution and relative abundance of coral reef fishes.

There was an error published in J. Exp. Biol. 220 , [186-193][1]. The surname of Sam Van Wassenbergh was incorrectly displayed. This has been corrected in the online full-text and PDF versions. The authors apologise for any inconvenience this may have caused. [1]: /lookup/volpage/220/186?iss=2

The ejection of internal organs, i.e., evisceration, is a well-known phenomenon in sea-cucumbers. We report the ability of a member of the Chordate phyla, the tropical ascidian Polycarpa mytiligera, to eviscerate and regenerate its gut within 12 days and to rebuild its branchial sac within 19 days. Evisceration occurred within 4–43 seconds of gentle mechanical pressure exerted on the tunic in 47% of the tested P. mytiligera. Individuals were able to discard up to 3/4 of their digestive tract via the incurrent siphon by rupture of the branchial sac in this area. Although chemical analysis revealed no significant levels of toxic compounds, the eviscerated guts were unpalatable to the triggerfish and pufferfish on which they were tested, suggesting evisceration as a defense mechanism. Given the close affinity of ascidians to vertebrates, the regeneration pathway of the viscera and branchial sac of ascidians suggests its potential beneficial application in soft tissue regeneration research.

Here we provide the first documented occurrence of the yellow tang Zebrasoma flavescens and of the clown triggerfish Balistoides conspicillum in the Mediterranean Sea. These tropical fishes were photographed in October 2008 off Sitges (Costa Daurada, Spain: 41°13'27.09" N; 1°47'22.35" E) and in July 2012 in front of Palamós (Costa Brava, Spain: 41°50'56.19" N; 3°8'26.29" E), respectively. Their possible release from private aquaria is discussed.

Ciguatera fish poisoning (CFP), the most common nonbacterial illness linked with eating fish, arises from the ciguatoxin produced by Gambierdiscus algae in tropical and subtropical areas of the Pacific, Western Atlantic, and Indian oceans.1 In this issue of EHP investigators assess the relationship between climate variability and reports of CFP, concluding that incidence of CFP is likely to increase with rises in sea-surface temperature and tropical storm frequency.1 Ciguatoxin bioaccumulates up the food chain as herbivorous fish eat the algae and are themselves eaten by carnivorous fish.2 The odorless, tasteless toxin withstands freezing and cooking, and people who ingest it begin experiencing gastrointestinal, neurological, and sometimes cardiovascular symptoms within hours of exposure. The symptoms usually resolve after a few days but may linger for months or years, or return after apparent recovery; death is rare. An estimated 50,000–500,000 cases of CFP occur annually worldwide.3 CFP is thought to be a widely unreported illness.4 Gambierdiscus algae (inset) produce a toxin that contaminates reef fish such as red snapper, triggerfish, and mackerel. Climate change is predicted to increase sea-surface temperatures in some areas, which could allow harmful marine algae to become more prolific over a wider territory.4,5,6 In the current study, the researchers hypothesized that CFP incidence increases in conjunction with warmer sea-surface temperatures and increased tropical storm activity. “What we were interested in is the extension of ciguatera into the mainland United States, either from fish importing or through expansion of the endemic area up the sea coast,” says Daniel Gingold, who led the study at Emory University. “It’s possible that the biggest change [in incidence] that would happen due to climate change is not actually in places where it’s already endemic—it may occur in places that used to not be able to support ciguatera but now do.” Information on possible CFP cases during 2001–2011 came from the National Poison Data System; the data comprised 1,102 calls to poison control centers in the continental United States, Puerto Rico, and the U.S. Virgin Islands. Cases were grouped by month and analyzed with monthly sea-surface temperatures and severe tropical storm activity in the Caribbean during 1999–2011. The model incorporated lag times of 0, 3, 6, 12, 18, and 24 months between weather events and reported CFP cases. Lyndon Llewellyn, research manager at the Australian Institute of Marine Science, characterized these lag times as an important aspect. “There will often be a delay between the initiation of ciguatera flowing through the ecosystem before human poisonings are observed,” he says. Llewellyn was not involved in the study. Based on their analysis, the investigators estimated that each additional storm in a month was associated with an 11% increase in CFP-related calls 18 months later, and that each 1°C increase in maximum sea-surface temperature during the month of August was associated with a 62% increase in calls after a lag of 5–16 months.1 These results were then considered in light of predictions about climate change. Assuming a 2.5°C increase in maximum Caribbean sea-surface temperature and a 10% increase in storm frequency, the researchers estimated an additional 239 CFP-related calls per year. The maximum estimated increase was 461 calls.1 There are numerous caveats to the findings. “The sea-surface temperature projections in the tropical Atlantic by our climate models are really bad,” says Vasu Misra, an associate professor of meteorology at the Center for Ocean-Atmospheric Prediction Studies, The Florida State University, who was not involved with the study. “So, attribution of climate to CFP incidence is a very difficult task.” Misra also notes a growing consensus that overall Atlantic storm frequency may go down in the future climate, although more intense storms may become slightly more frequent. Additionally, it was impossible to confirm CFP cases, fish origin, and location of exposure, and factors such as tourism and changes in fish consumption over time were not controlled.1 “We are missing a lot of information about this whole question,” says Gingold. “It’s been hypothesized for a long time that ciguatera would be affected by climate. But we really don’t have enough data to answer this question yet—we don’t have enough years of data, and we don’t have a very good surveillance system for identifying the toxin in commercial fish or for confirming actual cases.” Whether as an emerging disease in nonendemic areas or a neglected tropical disease in endemic areas, ciguatera and Gambierdiscus algae both warrant scrutiny.2 The limitations in this study generally pervade ciguatera research, says Llewellyn, who adds, “This paper is a good example of what is needed—biomedical professionals, especially epidemiologists, focusing on ciguatera.”